1. Field of the Invention
The subject matter disclosed generally relates to the field of semiconductor lasers.
2. Background Information
Semiconductor lasers are used in a variety of system applications. For example, semiconductor lasers are used as a light source in fiber optic communication systems. It is generally desirable to provide a semiconductor laser that has a high power output. High power output reduces the number of repeaters and amplifiers required for the optical system.
Increasing the power of a semiconductor laser can result in higher optical power densities in the laser. High power densities can cause damage to the laser, particularly at the output mirror, reducing the useful lifetime of the device. Additionally, high optical power density can lead to non-linear effects in the laser beam. The non-linear effects degrade the quality of the beam and the overall performance of the optical system. The optical power density can be lowered by increasing the width of the active light-generating section. Unfortunately, widening this section may cause the laser to emit light in a multiplicity of lateral modes, thereby degrading the optical quality of the laser""s output.
U.S. Pat. No. 4,856,017 issued to Ungar discloses a semiconductor laser that has a distributed feedback laser section and an amplifier section. The distributed feedback laser section includes a diffraction grating for generating a coherent beam of light. The coherent light beam is then amplified in the amplifier section. The amplifier section is tapered so that the output facet is relatively wide. The wide output facet reduces the optical power density at the facet. The lower optical power density improves the life of the semiconductor laser and the quality of the resulting light beam.
Further increasing the power of the Ungar semiconductor laser would require enlarging the amplifier section and the overall size of the die. Enlarging the die increases the cost of mass producing the semiconductor laser and reduces its efficiency. It would be desirable to increase the output power of the semiconductor laser without enlarging the die. Conversely, it would also be desirable to reduce the die size without reducing optical power.
A semiconductor laser that includes a distributed feedback laser section and an amplifier section. The semiconductor laser also includes a reflective element located along an optical path between the distributed feedback laser section and the amplifier section.